Introduction

Nowadays with broadband Internet, DVDs and hard disk drives over 120 GB the necessity for high-capacity mobile storage is greater than never. You may need to copy some files at a friend’s home or even make a backup. Flash USB drives are a convenient way to carry data around, but they are not available with capacities beyond 4 GB yet. X-Micro has just released a very small external hard disk drive that promises to fill this gap, named Mini DisGo.

We adopted a 3% error margin. So, performance differences below 3% cannot be considered meaningful. In other words, products where the performance difference is below 3% must be considered as having similar performance.

Performance

The program we used to measure hard disk drive performance, DiskSpeed32, reads all hard drive sectors, plotting a chart with all transfer rates obtained.

We included in our comparison another small external hard disk drive, Anypak, manufactured by USBNet, from South Korea. We also included on our comparison the performance obtained by other USB external hard disk drive enclosures (SPIO from ValuePlus, HardBox from Sarotech and 5000XT from Maxtor, which can also use FireWire port). We also included in our comparison the results from some hard disk drives connected to the standard ATA port, in order to see the difference in performance between an USB hard drive and a standard parallel IDE hard drive.

Normally the hard disk transfer rate varies according to the part of the disk that is being read. The disk transfer rate is higher at the disk's edge, lowering as it approaches its center. This occurs because of the zone bit recording (ZBR): in longer tracks (the ones away from the disk center) there are more sectors and more data is read at each disk spin. Because of that, the software used shows three results: maximum transfer rate (obtained on the first disk cylinders, i.e., on the tracks located near the disk edge), minimum transfer rate (obtained on the last disk cylinders, i.e., on the most inner tracks), and average transfer rate, which is the result that we are usually interested in knowing.

Because of this effect we can also explain the need of hard disk defragging and why professional disk defrag utilities such as Norton Speed Disk allow you to move the operating system files to the beginning of the hard disk. As we explained, data stored on the beginning of the disk are read at a higher transfer rate than data stored in other sectors.

On the graph below you see our benchmarking results (in KB/s) and our analysis.

X-Micro DisGo 20 GB obtained the worst performance in our comparison, however these numbers are not final because we are comparing apples to oranges. First, notebook hard disk drives spin at a lower rate, thus achieve a lower performance.

The product that really competes with DisGo is USBNet’s Anypak, since both use notebook hard disk drives. Anypak achieved a maximum transfer rate 36.28% higher and an average transfer rate 45.14% higher than DisGo from X-Micro. However, the Anypak model we tested was carrying an 80 GB 2.5" hard disk drive from Fujitsu, and a correct comparison would have to compare both models with a hard disk drive with the same size and capacity.

Conclusions

Even tough its performance is not similar to a hard disk drive directly connected to the system IDE port or even to other USB 2.0 solutions available on the market, the main advantage of Mini DisGo from X-Micro is its size and weight, being perfect for carrying it in your purse, in your pocket or in the glove compartment of your car. It is really handy for copying files when you are visiting a friend, for example. As we already said, we were impressed by its size and weight.

Its cable is too short and you will need to use the hard disk drive very close to your USB port. On the other hand, its very short cable is easier to carry in your pocket than a long cable. An ideal solution would be a retractable USB cable.

As for the price, the Toshiba hard drive used on the reviewed model can be found at USD 110~135 range in the USA market, so you are actually paying USD 34~59 for the enclosure and for getting everything already assembled and ready to use.

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